Heat sink for a lamp



FIG. 1 is a perspective view of the new design for a heat sink for a lamp as seen from the front, top;

FIG. 2 is a rear perspective view as seen from the rear, side thereof;

FIG. 3 is a side elevational view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a rear plan view thereof.

The broken lines illustrate portions of the lamp other than the heat sink to show environmental features only and form no part of the claimed design. 

CLAIM The ornamental design for a heat sink for a lamp, as shown and described. 